A cobp



A. W. PEARSALL.

PNEUMATIC DESPATCH TUBE APPARATUS.

APPLICATION FILED AUG-30. 1912.

1,31 1,617. Patented July 29,1919.

2 SHEETS-SHEET I /Zzlr ATTORNEY.

THE coumam PLANOGRAPH c0., WASHINGTON, n. c.

A. W. PEARSALL.

PNEUMATIC DESPATCH TUBE APPARATUS.

APPLICATION FILED AUG-30, 1912.

1,31 1,617. Patented July 29,1919.

2 SHEETSSHEET. 2.

- WITNESSES: INVENTOR.

Z1": ATTORNEY.

COMPANY (FORMERLY 'LA' sonoo isot pl'i n fron'n s avme cerium or BOSTON, MASSACHUSETTS, acoar ormrroiv or JERSEY. I

' mmvii msmwomeee Af'PARAj'ine Specificatienef Letters ratent. I

Application filed August 30, 1912-. 'snai N6. 17,83?i.

To all whom it may concern. I

Be it known that I, ALBERT W. PEARSALL, of Lowell, in thec'ounty of Middlesex and Commonwealth of Massachusetts; have invented certain new and useful Improvements in Pneumatic-Despatch-Tube Apparatus, 'of which the following is a specification. i

This invention relates broadly to automatic pumping app aratus and inore'p articularly to pneumatic despatch tube systems and the pumping apparatus therefor and has for one of its objects theprovision of means for automatically starting an evhauster, blower, pump or the like; which may be broadly termed a pump and which forms a part of the apparatus in question, and there after automatically regulating or governing the action of said pump or blower to meet the service requirements of a pneumatic despatch tube System; bringing the pump or blower to a state of rest when all servicerequirements have been met.

Another object of my invention is to increase the efficienc'y of systems of this character by econ'oinizing power; new instrumentalities being employed to this end.

I preferably aim to control the action of the eXhauster or blower through its prime mover or motor, but do not wish to 'be limited to such means. lVl'ien Such control is eXer cised overthe'priine mover, it is desirable that the latter be a singlep'ower unit of sufficient capacity to meet themaximum service requirements of a system of pneumatic tubes of one or more air circuits ,and that the control exercised be Such as to maintain, when in operation, a substantially constant Working force; the volume of the air displaced being automatically varied in accordance with the demands of the Service. In the pre ferred form of apparatus the means for controlling the power unit are adapted to bring it to rest when all useful service has been performed; mechanism being provided for utilizing a relatively slight variation inpressure in the fluid transmission medium, from a given predetermined pressure required or provided for the operation of a given pneu- Inpractice saidhauste d, when the air displacing device'is beingdriven at a normal maximum speed; but may be due to other causes.

Another object of my inventibn is to provid'ea device in connection with said mechanism wherebythesystein when it has been started working may, after the attainment of "proper o erative conditions, then beheld in operation for a predetermined and limited interval of'time before automatic stoppage, means being provided for "c'oaction with said device for preventing the running of this iiiterval of time until "said conditions first liav been established.

- The preferred power unit is an electric motor and I have aimed to incorporate in the system in connectioi'i with such motor an autoi'natieally actuated field controlling rheostat, the'oper'ative part ofwhicl'i will normally be in such a position as to'perinit the motor being" automatically started from a state of rest without weakening the field circuit thereof by the introduction of external resistance. r 7

These and other objects of my invention will be hereinafter referred to and the-novel elements and combinations of elements whereby they may be attained will be'more especially pointe'dout in the claims appended hereto. 1 A

I- am aware, however, that various changes and modifications 'be made in the, system hereinafter more particularly described without-departing: from the spirit of their ve'ntion, and I hence desire tob'e limited only by the scope of said claims.

v The preferred embodiment of invention comprises a single power unit which is normally at rest this power 'unit preferably being a Shunt wound electric motor Which is operatively connected to an exhauster. This latter is adapted through the instrumentality of suitable pipe connections leading to a suction druimto create 'a pressure below that closed valve which is preferably electrically controlled. The compl'etionof a-l-ow voltage electric circuit at any despatch inlet or 'station' of a pneumatic" despatch tubeeircuit ALBERT w. PEARS'ALL, or LOWELL, iviassaefriii snris, nssr'eivoa 'ro LA visoiv reteateii .iiu y aim-9;

serves to open thesaid electrically controlled valve atthe suction drum of that line, and also to actuate a relay which completes an electric circuit whereby to cause the operation of an automatic motor starter, bringing the motor'up to its minimum speed and sub-. stantially coincident with the attainment of this minimum motor speed, the completion of an electric circuit which energizes an electromagnetic device, mounted on the field controlling rheostat, which withdraws a latch or pawl and thereby releases the arm of said rheostat. The rheostat arm is then free to move, preferably under the influence of gravity, in such a direction as to cut in resistance in the motor field and increase its speed aswell as that of the'exhauster'to which it is operatively connected; providing that a pressure adequately below that of the atmosphere has not already been attained in the given tube circuit; said pressure being such as Will, under the conditions imposed, result in the displacement per unit of time of a suflicient volume of air to 'make'the tube circuit efficiently operative.

Figure 1 is a somewhat diagrammatic view of a preferred form of the apparatus in question; this figure particularly showing a controlling panel used therein, its connections to a shunt motor, and one of the pneumatic despatch tube control circuits. V

Fig. 2 is a front elevation of an electrically actuated air valvewhich is dominated by one of said control circuits.

. Fig. 3 is a vertical median section of said valve. 7

Fig. 4 is atop View or plan of the same. Fig. 5 is a detail section of said valve. 7 Capital letters have been applied to principal parts of the apparatus, small letters to details of these parts, and numerals to the various subsidiary elements of the electrical equipment, the numerals being arranged in? groups of ten or less with each group applyi g; as far as practicable, to related connections or parts.

Motor and connections thereto.

. Referring first to Fig. -1, a panel A has mounted thereon a main line double pole switch B, main solenoid switch C, and low voltage relay D. Electrically connected to this panel is a motor E, preferably of the variable speed, shunt-wound type, the field circuit of which motor includes a rheostat F. The latter is also mounted on the panel together with an automatic motor starter G.

has a bias for its open position, is drawn down, in the manner hereinafter described,

it makes contact not only with this post but with two other posts,-11 and 12. r

The 'efiecting of contact between the arm C and posts 11 and 12. completes two partial circuits; the current flowing through contact 12 maintaining said arm in its circuit closing position; while the current flowing through 11 energizes the coil of the motor starter Gr.

The actuation of the motor starter G first establishes the field circuit of the motor and current flows from the now energized switch arm C through wire 13 and lead 20, to the field coils 21; thence via lead 22 and wire 23 to the plate 30 of rheostat F, and from there over wire '31 to the contact strip 40 of the motor starter G. The starter arm 41 will, under the described conditions, have moved upwardly into contact with strip 40 and the field current will traverse this arm to pivot post 42, flowing thence o'ver wire 43 to the fuse 4', switch B and line wire 1. Following the partial circuits above referred to in detail, current flows from post 12, through wire 14 to the solenoid switch C,

thence via wires 15 and 16, resistances 17 and 18, and wire 19 to the pivot post 42,

from whence it flows toward lead 1, over wire 43, fuse 4 and switch B.

Current through post 11 traverses wire 44, the solenoid 45' of the motor starter, wire 46, lamp switch 47 and wire 48 to the pivot post 42, and thence on to lead 1 as above described. I I V V The energization of coil 45 causes the arm 41 of the motor starter to swing upwardly in themanner described so that it successively engages first the contact plate 40 above referred to and thereafter the con.- trol plates 49.- 7

No considerable armature current can flow until the movable contact 50 carried by arm 41 engages the first of the segments 49 which is electrically connected to the resistance 49.

Then this contact is effected however. current flows from' lead 20 through armature 24, lead 25, wire 26, contact 27 wire 28, resistance 49 and contact 50, toand through arm 41, and from thence out via pivot post 42, wire 48, etc.

As the arm 41 continues to'moveupwai'dly, resistance iscut out .OfllllO armature circuit and the motor speeds'up.

It is desirable that a slight excess of speed be attained in order to insure the proper actuation of the rheostat controlling device H, hereinafter referred to, and hence in certain cases means may be provided for in-' troducing a resistance 30 in the field circuit. To this end, a series of contacts may heprovided in arcuate alinement with the contact strip i0, so that as the extremity of the arm 41 leaves the latter it successively receives the field current from wires 32, 33, 34:, 85 and 36 instead of from wire 31 as hereinbefore described. 7

At or about the time that the arm 41 encounters the last of this series of contacts, a yielding or spring contact 51 carried thereby engages a fixed contact 52, which energizes a magnet 37 mounted on the base of rheostat F; magnet 37 receiving current via wire 38 from the wire a4: above referred to, and the circuit being completed through wire 39, contact 52, spring contact 51, arm 41, pivot post 42, wire 43, etc.

Upon the arm 4:]. is a pin shaped, lamp switch operating finger 410 whichwhen the arm reaches substantially itsuppermost p0 sition, lifts the lamp switch 47, the upper end of which may be pivoted, and current no longer flows through said switch.

The resistance 47 in shunt with switch 4L7 becomes effective at such time and reduces the flow of current through coil to a point where the magnetic field of the latter is just sufficiently strong to retain the arm ll in its upper position. This ob viously cuts down the heating of coil 45 and prolongs its life while economizing current.

Field rheostat Gomez.

It will thus be seen that the magnet 37 will 'be energized by a StlOllg current which will attract the armature 60 carried by. a pawl-61 and thereby effect the release of the field rheostat arm- 62; permitting its movement counter clock-wise b'y the apparatus H and cutting in further, resistance in the .field circuit, causing the motor E-to speed up. and drive the blower or pumpl until a sufficient volume of air is being displaced from the drum J (to which .the pump is connected by a conduit or pipe K) at the determined pressure for which a weight a of the apparatus H has been adjusted.

lwovement is imparted to the rheostat arm 62 through the instrumentality of an insulaing link L, which is pivotally connected to the head of a piston rod-Z9. This rod is carried by a piston 0 which is adapted to reciprocate in a closed cylinder (Z. The upper extremity of the latter is connected by a pipe M to the, drum J above referred to, and the lower end of said cylinder is provided with a service cock H which opens to the atmosphere and permits of regulation of, the speed ofmovement of said .piston. The pipe M is also, provided with a cock M to the same end.

Rodb extends through both heads of the cylinder'and carries the weight a at its lower extremity, said weight being varied to suit the particular conditions under which the system is to be operated.

Fluid pressure .Z-iam't.

Upon the side of the field rheostat arm 62 and insulated therefrom is a contact brush 6.3 which is adapted to complete a normally open partial circuit by contacting with posts 64 and 65. This partial circuit draws current from the, wire let; the switch G being closed in manner aforesaid. This current passes via wire 66 to contact post 65, thence through brush 63, post 64: and wire 67 to wire 16. In other words this so com pleted circuit is in parallel with the main solenoid switch coil and hence when the arm 62 of the rheostat rotates clockwise to the limit of its travel, it short circuits the main solenoid switch, causing it, on account of its weakened solenoid, to open.

This disposition ofcthe arm 62 is brought about by the development of a rarefication of the air in the upper endof the cylinder d, in excess of a determined amount, which of course is due, in turn, either to excessive speeding of the motor and thereby of the pump I, connected thereto by the belt I or the like; or to the substantial closure of the air inlet to the drum J while the motor is in normal operation.

Air oaloc.

The drum or reservoir J receives air from at least one tube N in a known manner, and in this tube I provide an air valve 0 for the purpose of controlling the flow of air through the individual transmission lines or transit tubes.

In Figs. 2, 3, 4: and 5 I have exemplified a preferred construction of said valve which is herein shown to comprise a casing c within which is pivotally mounted a hinged valve plate f which carries a disk 9 of leather or the like. Plate 7 is loosely mounted upon a shaft h the end of which carries a ratchet 2' adapted to co-act with a pawl j whereby a spring 70 mounted on said shaft may be placed under any desired initial or normal stress. The end of the spring 70 other thanthat attached to the shaft h'bears against the hinge plate and normally holds the valve against its seat Z. Plate f carries 3 lug m which extends through disk 9, said lug being connected to a link a the other eX- tremity of which is connected to a lug 0 of a diaphragm supported structure p. This latter may be of any suitable construction and is carried by a diaphragm g the periphery of which is clamped between the casing members 6 and r. The diaphragm is normally forced back by spring is into a cavity 8 in the member 1", and a conduit or passageway 23 leads from this cavity to a port a which opens to the atmosphere when the valve c which is normally seated upon the mouth of this port is lifted. The spaces upon the respective sides of diaphragm Q are in communication through a small port or bleed hole w; the fiow of air through said hole being controlled by a valve 00.

The valve 41 is disposed upon the lower ex tremity of the core 7) of a solenoid P; the

upper end of said core beingprovided with a barb or hook g which is adapted for engagement with a spring latch or catch 3 The latter is given a determined bias for its latching position'but may be displaced therefrom by a diaphragm 2 which covers a recess 2 in the outer side of the casing 6; said recess being in communication with the main air passage in said casing through a preferably, although of course not necessarily, small hole (2. The resistance offered by spring catch y to displacement by its diaphragm 2, may be varied by the set screw a2 and determines the pressure which must be exerted against the diaphragm e in order to cause it to move to the left, as viewed in Fig.

3, to effect the release of the hook y. Ob-

viously, once the hook g has been latched up,

only the establishment of a determined pressure, or rarefication of air below atmospheric pressure in the conduit N and, by reason of the hole 6, correspondingly upon the left-hand side of the diaphragm 2, will effect the release of said hook.

Relay and airwaloc solenoid circuit.

The relay D, above referred to, controls the main solenoid switch C since when its coil is energized and the core 71 thereof is thereby lifted, the contact piece 72 carried by its core makes contact with posts 7 3-74 and allows current to flow from the post 7 3 through contact 7 2, post 74, wires 66 and 14, the winding or coil of switch C, wires 15 and 16, resistance 17 and 18, wire 19, pivot post 42 and thence out as above described.

The actuation of relay D is a preferably elfected through the instrumentality of a low voltage circuit such as I shall now describe.

A battery Q may be used as the source of low voltage current, a wire leading therefrom being adapted tobe placed in electrical communication with either one of the respective air valve solenoids P. Solenoids P and 70 are in series; being connected by a wire 81; and the current returns to the battery via wire 82.

Circuit makers R and S dominate the respective solenoids P, those designated R being disposed at sub-stations of the tube line while those marked S may be located at the central station. These circuit makers may, if desired, be operated entirely independently of the operation of inserting a carrier into the despatch inlet, but I do not Wish to be limited to this construction except where, in certain of the claims, such independence is specified.

Operation.

The closure of the low voltage circuit at any one of these stations R and S hence effects two results; the relay D is energized and thereby the motor is automatically started and regulated in the manner above described; and the corresponding solenoid P is rendered operative andits core 12 is raised and latched up by the spring catch 3 As previously described, the motor field is first energized and then the armature is per mitted to receive a gradually increased current; resistance being automatically successively cut out of the armature circuit and into the field; the resistance in the armature circuit after the starting arm 41 reaches the position thereof indicated by dotted lines in Fig.1, being merely a protective one; the lamp switch 47 being open, and the armature current passing from contact 27 directly to contact 27 via abridge 41 carried by the starter arm 41, and from thence over wire 48 to pivot post 42 and out.

A momentary closure of the low voltage circuit is sufficient to accomplish the results just enumerated since the closure of switch C establishes its own maintaining circuit, above described, after which only the development of a rarefication of air in the actuation of solenoid core 29, then the piston 0 will be raised to its uppermost position,

which short circuits thesolenoid switch in the manneraforesaid and permits its arm C to rise.

While the rheostat arm 62 is at all times free to be forced back into its solenoid switch opening position, it cannot move past the pawl 61 until the starter arm 41 attains its uppermost position. After the arm 41 has been so disposed, however, the raising of pawl 61 by its magnet 37 permits the rheostat arm to respond to the fluctuations inpressure in the drum and to thereby cut resistance into or out of the field as required the piston descending as the pressure falls and thereby introducing resistance in the field and speeding up the motor.

Normally the airvalve O is closed since the bleed hole 10 permits of an equalization of pressure upon the opposed sides of the diaphragm 9; but the elevation of the core of solenoid P by the energization of the latter, lifts the valve 4) from its seat and ad'- mits air to chamber 8 which drives the structures 29 into the'casing e and lifts the valve disk g; the valve opening covered by the latter being of less area: than said diaphragm.

Air now passes through the transmission tube, it being assumed of course that the sending end of the latter is open or has been opened, and enters the" drum J, partially breaking the vacuum inthe latter.

As the rarefication of air in the drum becomes less, the weight a descends and resistance is cut into the motor field which speeds up the blower or pump and tends to restore the vacuum and thus a regulating or governing action will normally be exerted as long as air valve 0 remains open.

The rarefication in tube or conduit N, however, due to the opening of the air valve, had previously resulted in the auxiliary diaphragm 2 being drawn into' the cavity 2' which released the barb 3/ of core 7) from its catch allowing said core to fall and closing the port a. Thereafter the air in cavity 8 slowly seeps out through the bleed hole w, allowing the spring is to correspondingly close the air valve.

The closure of this valve results in an immediate rarefic-ation of the air in the drum and causes the piston c to ascend and to thereby successively cut resistance out of the field, decreasing the speed of the motor and the blower connected thereto, and finally effooting the closure of the" short circuit around the main solenoid switch. lhe opening of the latter stops the motor, the starter arm 41 descends,- pawl 61 falls and locks the rheostat arm against further movement away from the, contacts ti l-65, the Weight of the piston efiectin'g, however, a proper separation of these contacts from the brush 68 which co-acts therewith, and the apparatus is then set preparatory to a re-actuation ot the same.

The catch y cannot be tripped against the action of the spring inherent thereto until a predetermined pressure, sufiiciently below that of the atmosphere, has been established in the transmission tube of which tube N may form a part, and it is obvious also that the closure of the cut-off valve 0 takes place more or less rapidly according to the flow or pressure of air in the transmission tube and the amount of opening afforded by the valve 00.

The set screw 00 affords a very simple.

means for determining the operating pres sure at which the spring latch y W111 yield suflicicntly to permit the time element mechanism to come into operation.

mission purposes. Y

The manner in which carriers are transmitted by means of pneumatic circuits T, such as have beenindicated in .Fig. 1-, is so well: known to thosenskilled in the art as to require no specialdescription herein.

In conclusion, I particularly desire to point out that while the time element meohanism employed herein is adapted to effect the closure of the air valve 0 in a determined period of time after the development Y of a determined pressure or rarefi'cation of minute: It now, a more nearly complete vacuum be attained, for any cause, the period will necessarily be of shorter duration, but though different from the first, will: nevertheless be a determined period; being determined by the position of the valve 00 and the pressure or pressures in a given tube N.

As a matter of fact: Owing to the pro- 9 vision ot the means for regulating the speed of the" pressure fluid displacing device and thereby the pressure in the system, but relatively small variations in pressure can normally occur other than possiblemomentary" changes due to the opening and closing of inlets, and the like. a i Y Y The variable action of the time element mechanism, however, is of value in that it especially well adaptsthe system to the conditions encountered in practice in a system such as has been herein described.

eo pen'ding" application for Letters. Patent, Serial No: 16,472,- entitled Pneumati'c despatch. tube apparatus, which wasfiled' March 23, 1915, is a division of the present case; the subject matter of said 'divisional application having first been pre sented herein and thereafter duly divided out of this, the parent application;

'Olai s:

1. In a pl'letlllifltic despat'c'h tube apparatus, the combination of an electric motor having a field circuit, pump, an electromagneti'cal'ly operated device for starting 12 said motor, co-acting 'inea'ns for insuring the motor being started with said field circuit relatively strong, fluid actuated means vfor varying the conditions in said field circult whereby to vary the speed of said mo- 1 25 tor, and pressure fluid controlled means for stopping said motor when said pump produces a redetermined pneumatic pressure which is 1n excess'of that required for trans- 2. In a pneumatic despatch tube apparatus, the combination of an electric -motor having a field energizing circuit, the speed of said motor being variable in accordance with the conditions in said circuit, a pump driven by said motor, motor controlling means a portion of which isadapted to-coact with said circuit, said means comprising -an electro-magnetically operated'device for starting said motor, fluid actuated'means for varying the conditions in said circuit and thereby the speed ofsaidmotor, and pressure fluid controlled means for stopping.

said motor When said pump produces a p1'e determined pneumatic'pressure which is in excess of that required for. transmission purposes.

3. A- piieuinatic despatch tube system 1 comprising a conduit, a. pump operatively connected thereto, means, including a low voltage electric control circuit, for render ing operative said pump, and automatic 'means for varying the speed of said pump when in operation according to the service demands of the system and for rendering said pump inoperative when the pressure fluid in a determined portion of said system exerts a predetermined pressure.

4. A pneumatic despatch tube system comprising a conduit, a pump operatively connected thereto, an electric motor for drivmg said pump, said motor havingarmature and field circuits, fluid pressure controlled means co-acting with one of said circuits for varying the speed of said motor substantially in accordance with the service requirements in said system, and means for maintaining said last mentioned means substantially inoperative until predetermined conditions have been established in a circuit of said motor.

5. A pneumatic despatch tube system comprising a conduit, apump operatively connected thereto, an electric motor for driving said pump, said motor having armature and field circuits, fluid pressure controlled means co-acting with one of said circuits for varying the-speed of said motor substantially in accordance with the service require ments in said system, dHCl'IXlGiIHS for maintaining said last mentioned means s'ubstan- .tially inoperative until predetermined conditions have been established in the armature circuit of said motor.

6. A pneumatic despatch tube system comprising a conduit, a pump operatively connected thereto, an electric motor for driving said pump, a starting device for said motor, means for rendering said starting device operative, said starting device having a part adapted to move in a determined path, a rheostat having a movable member for controlling said motor when in normal 7 operation, means controlled by said partvof said starting device for initially impeding position.

the system.

the movement of said member, and pressure fluid controlled means member.

7. .A pneumatic despatch tube system comprising a conduit, a pump operatively connected thereto, an electric motor for driving said pump, a starting device for said motor,.said starting device having a movable part, means including a low voltage cir cuit having a relay ther in, for rendering for actuating said said starting device operative, fluid pressure controlled means for varying the speed of said pump, said motor having armature and .field circuits, means for controlling one at least of said circuits,'said means including an electro-magnetically controlled switch, means for closing said switch and starting said motor and pump from a distant point along SiLlClCOllClLlll'j and means for insuring the opening of said switch when a determined fluid pressure is developed in a deter mined portion of said'system.

9. Apneumatic despatch tube system comprising a con'duit,'a pump operatively'connected thereto, an electric inotori'i'or driving said pump, said motor having armature and field circuits, means for controlling said'circuits, said means including a main switch,

means for closing said switch from a distant L point along said conduit and means for 1n suring the opening of said switch when a predetermined fluid pressure is developed in a a determined portion or said system.

10. In combination in a pneumatic des patch tube apparatus, a conduit, a pump operatively connected thereto, an electric motor for driving said device, a starting pump ior said motor, a rheostat for controlling said motor when in operation, fluid pressure controlled means for actuating a part oi said rheostat, a valve in said conduit, fluid pressure controlled. means for actuating said valve, and means co-acting with said valve,

.said rheostat part and the means for actuating the latter, for insuring the stoppage of the motor when a predetermined fluid pressure is attained in a determined portion of 11. A pneumatic despatch tube apparatus comprising an exhauster, an electric motor for driving the. same, a normally open, electro-magnetic main switch for said motor, a low tension circuit including a relay for initially controlling the flow of current through said main switch, a motor starter in circuit with said switch, a. maintaining circuit for said switch when closed, and means for insuring the opening of said switch. substantially; when a predetermined rarefication of the airv is effected. by. said .eXhauster in a portion of said system."

switch substantially when a predetermined pressure of air is produced by said pump in a portion of said'conduitl.

13. A pneumatic despatchtube apparatus comprising a conduit, an eXhausterv corinected thereto, an electric motor for driving the exhauster, and means "for; starting the motor,'in combination with means for regulating the speed; of the motor in response to pressure in the conduit when the motor is permitted to. run, and, automatic means acting in consequence of: occurrence of flow of air through said" conduit for stopping the motor, said automatic means being operative after. flow at a predetermined pressure during a predeterniinedihterval of time, and being'inoperative prior to establishment of flow at such pressure.

14. A pneumatic despatch tube apparatus comprising, a conduit, an exliauster connected thereto, an electric motor for. driving said exhauster, and means for starting the motor, in combination. with automatic 'means acting in consequence of 'occurrenceof flow. of

air through said conduit for stopping the motor, said. automatic meansbeingj operative after flovv at predetermined pressure for a predetermined interval of time, and being inoperative prior to establishment of 'flOW at such pressure.

15. A pneumatic despatch tube system comprising-a conduit, a pump. for said conduit, means for regulating the action of said pump, said means including a movable part' the position of which substantially determines the speed of said pump, means for holding said part against movement in one direction untilsaid pump is running substantially normally, means for releasing said part when such cond-itionis attained, and means for moving saidpart in accordance with variations in pressure in a part ofsaid. system.

16 A pneumatic despatch tube system comprising a conduit, a pump. for said conduit, means for regulating the action of said pump, said means includingv a movable part, the position of which substantially determines the speed of said pump, means for. holding said part againstmovement in determinesthe speed for'holdlng said part agalnst movement 111 mg said pump,

one direction until. said pump is running substantially. normally, meansfor, releasing said'part' when such condition is attained, means for. moving said part in accordance withvariations in pressure in a part of said system, and means'co-acting With said regulating means for stopping said pump upon the development of a predetermined pressure in a portion of said system.

17. A pneumatic despatch tube system comprising a'conduit, a pump for said conduit, means for regulating the action of said. pump, said. means including a movable part, the po sition of Which substantially of said pump, means one direction until said pump is running substantially normally, means for releasing said part when such condition is attained, means for moving said part in' accordance with variations in pressure in a part of said system, and means co-acting with said part for stopping said pump upon the developmentof a predetermined pressure in a portion of said system, said part being movable for co-action With the last mentioned means even when held against movement in one direction in manner aforesaid.

'18. A pneumatic despatch, tube system comprising a conduit, a. pump operatively connected to. said conduit, means for startmeans for maintaining it in operation, when started, at least until a given fluid pressure is attained in a determined portion of said system, means for adjusting 'a portion of said maintaining means to determine the given fluid pressure aforesaid at the amount desired, and means for normally stopping said pump Within a determined time interval after the attainmentof the given pressure in manner aforesaid. i i 19. In a pneumatic despatch tube system for carriers, having sendingand delivery stations, the combination of a conduit, a pump operatively connected thereto, means for starting said pump, said means includingv a controlling part therefor disposed substantially at said'sending station, said controlling part being movable lndependently portion ofsaid system.

20. A pneumatic despatch system of the type including a conduit for carriers and means causing carrier-driving changes of pressure in the conduit for the purpose of driving a carrier, having therein in combinationivith the conduit and the air-displac- 111 means therefor, a motor forv driving said means, automat c means for varying the speed of the motor: in response to the pressure in a part of the system, means for stopping the motor when the pressure reaches a predetermined l1m1t,a valve between the conduit and air-displacing means, electrically controlled means operated from a distant part of the conduit for opening the valve, and starting means for the motor a valve for throttling the flow of fluid through said conduit, means for operating said valve, means to co-act with parts of said valve operating means to determine an extended period of time during which said valve must remain open, an electric circuit for transmitting an actuating impulse to said valve operating means, means to prevent the running of said time period determining means and acting to restrain a part of said operating means against movement after being actuated by'said impulse, and fluid pressure controlled means for releasing said part upon the development of a determined pressure in said conduit, to permit the timing means to become operative.

22. In a pneumatic despatch tube apparatus, a conduit, the air in which is normally at atmospheric pressure, a pump connected thereto, a'valve for throttling the flow of fluid through said conduit, means for operating said valve, means to co-act with parts of said valve operating means to determine an extended period of time during which said valve must remain open, said pump be ing in communication through said conduit with the outer air only so long as said valve is open, means for transmitting an actuating impulse to said valve operating means, latching means to prevent the running of said time period determining means and acting positively to restrain a part of said operating means against movement after being actuated by said impulse until said pump has effected a departure from normalatmospheric pressure in a portion of said conduit in excess of a determined amount, and pressure responsive means for releasing said part from said latching means when the said departure from said pressure is attained.

23. In a pneumatic despatch tube apparatus, a conduit, the air in which is usually at atmospheric pressure, a. pump connected thereto, a valve for throttling the flow of air through said conduit, said valve 'having a bias for its closed position, means for displacing said valve from said position, time element means for controlling the movement of said valve back to said determined position when displaced therefrom, and means for rendering said time element means inoperative after said valve has been opened until a determined change in pressure of the air in a been attained. i I

24:. vIn a pneumatic despatch tube system comprising a conduit a part-of which constitutes a transit tube, a'pump 'operatively connected thereto, means for rendering said pump operative, time element means, means to be automatically operated after said pump has become operative, to coact with said time element means to establish a. de termined period of time andxto stop said pump at the end of said period, and automatic pressure responsive means to'cause said last mentioned means to establish said period only afterthe establishment :of determined pressure conditions in a part of said conduit. r a

25. In combination'in a pneumatic despatch tubesystem, having sending and delivery stations, a conduit, a pump operatively connected thereto, a mechanism for driving said pump, means for starting said mechanism and pump substantially simultaneously, said means including a controlling'element therefor disposed at a sending station in said system, and means controlled only in part by said controllingelement, for automatically stopping said; mechanism and pump afterthe lapse of a normally cletermined but extensible period of" time running only from and after the establishment portion of saidconduit has of a determined operating pressure in aportion of said system, each actuation of said controlling element ClUI'HI therunmng of 7 said period extending sai period by a determined amount, said last mentioned means including a normally closed valve in said conduit, means for openingsaid valve and means controlled by the pressure in said conduit and rendered inoperative when said operating pressure is established for maintaining said valve open'at least untilv said determined pressure is established;

26. In combination in a pneumatic despatch tube system, having sending and de livery stations, a-conduit, a pump operatively' connected thereto, a mechanism for driving said pump, means for starting said mechanism and pump, said means including a controlling part therefor disposed substantially at a sending station in said system, and means for automatically stopping said mechanism and pump after. the lapse of a normally determined but extensibleperiod of time running only from and after, the establishment of a determined ope-rating pressure in a portion of: said system, said last mentioned means including a normally closed valve and means 'controlledby the pressure in said conduit and rendered inoperative when said pressure is established for maintaining said valveopen at least until said determining pressure is established, said means for opening said valve being also controlled by the controlling part aforesaid and operatively responding to each actuation of said part during sald period of time to extend the latter. 1

27. In combination in a pneumatic despatch tube system, a branched conduit, a pump operatively connected thereto, a normally idle mechanism for driving said pump, a plurality of normally closed valves any desired number of which may be open at the same time, one of said valves being in each of the branches of said conduit to control the flow therethrough of pressure fluid displaced by said pump, means for substantially simultaneously starting said normally idle mechanism and opening any desired one of said valves, means, operable While said mechanism is in operatlon, for

, opening another of said valves, and means to close each of the opened valves after the lapse of a determined period of time, each valve being separately timed, said valve opening means each having provisions for extending by a determined amount said period for the valve corresponding to such means and during the running of said period.

28. In combination in a pneumatic despatch tube system, a branched conduit, a pump operatively connected thereto, a mechnism' for driving said pump, a valve in at least one of the branches of said conduit to control the flow therethrough of pressure fluid displaced by said ump, said valve being open or closed as esired When said pum is operative, and means, portions of Whic are common to both said mechanism and said valve, for starting said mechanism if idle and for opening said valve Whether said mechanism be idle or in operation.

29. In combination in a pneumatic despatch tube system, a branched conduit, a pump operatively connected thereto, a normally idle mechanism for driving said pump, a valve in each branch of said conduit adapted to control the flow through the corresponding branch of pressure fluid displaced by said pump, means for substantially simultaneously opening any one of said valves and independently of the latter to start said normally idle mechanism to drive said pump, means for maintaining said pump in operation so long as any one of said valves is open, and means co-acting with the last valve to close to automatically sto said mechanism.

n testimony whereof I have aflixed my signature, in the presence of tWo- Witnesses.

ALBERT W. PEARSALL.

Witnesses RALPH S. CLARKE, N. L. DONAHUE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0.. 

